The Snowman and The Snowdog, the officially-licensed Christmas 2013 game of the film, was developed by UK studio Big Bit and commissioned by Channel 4.

The “freemium” game includes in-app purchases, like many on the App Store. Players can buy boosts, upgrades and increase their snowflake reserve through the in-app purchase options to fast track The Snowman and The Snowdog's journey to the North Pole.

However, “to avoid bill shock” as Channel 4 puts it, you can't spend more than £20 without the game unlocking all content from that point - so a child's spend is effectively capped at £20.